Issue: No background music. Fix: U42 (music control PIA) outputs test OK with Leon ROM but corrosion in area. Remove U41/42 PIAs, clean corrosion, and add sockets. No continuity from U42-16/17 to SRC3, fixed. Install new U41/42 PIAs. Remove U37 (LS138), clean corrosion, and add socket. Install new U37 chip.
Tag: Williams System 11
Issue: Client reports switch errors and solenoid issues. Diagnosis confirms bad special solenoid channels, bad switch input and control outputs. Fix: Replace Q11 and Q12 with IRL530N.
Issue1: No kickback. Fix1: Clean mechanical assembly and adjust switch. Issue2: Ball stuck in locks, won’t kick out. Fix2: Replace bad fuse. Issue3: Left flipper lane change not working. Fix3: Fix end of stroke switch stack and fix reversed flipper pawl.